Once an OL (Office Lady) around 30 and born with memories of her past life, when Tsubaki was around 4 years old, from the words of her half-sister who she also thought held memories of her past life, she recalled that this world was from an otome game. In the game, the half-sister born from a lover was the heroine, and she was the villainess noble girl who tormented her. Furthermore, the END always concluded with a suicide. But in this world, there were a lot of differences in the setting. Thinking that she might be able to save her mother who commits suicide, it's a story where she does her best in protecting her mother and the main capture target character, her cousin, from her half-sister's devil like clutches.